SHH and neurodevelopmental disorder: Likewise, both in human and animal models, accumulating evidence indicates that impairment of the Shh–Smo pathway at postnatal stages may contribute to the emergence of neurodevelopmental disorders, including autism spectrum disorders (ASD) (Al-Ayadhi, 2012; Halepoto et al., 2015) and seizures (Feng et al., 2016; Su et al., 2017).